Circuit breaker variable resistor for power industry and regulation and control method thereof

Abstract

The invention relates to the technical field of electric power, and discloses a circuit breaker variable resistor for the electric power industry and a regulation and control method thereof, and the circuit breaker variable resistor comprises a control algorithm unit, a current detection unit, a displacement driving unit, a stroke amplification unit and a resistance regulation and control unit; the current detection unit is connected with the resistance regulation and control unit through the control algorithm unit, the displacement driving unit and the stroke amplification unit in sequence; the method comprises the steps that the current detection unit obtains current and judges whether the circuit is abnormal; calculating the resistance required by normal regression, obtaining the displacement of the displacement driving unit, and determining the voltage output to the displacement driving unit; the displacement driving unit displaces, and the stroke amplification unit controls the displacement of the moving contact, controls the tensile strength of the liquid metal and regulates and controls the resistance, so that the circuit is normal; and skipping to the first step. According to the invention, the piezoelectric ceramic is used as a displacement driving structure, the response speed is microsecond level, and the response is accurate and rapid; the liquid metal is used as a medium, the movement and resistance change speed is high, nontoxicity and harmlessness are achieved, the conductivity is high, and the chemical property is stable.

Description

Technical Field

[0001] This invention relates to the field of power technology, and in particular to a circuit breaker variable resistor and its control method for use in the power industry. Background Technology

[0002] In recent years, with the rapid development of new energy technologies, circuits in various fields have shown a trend towards larger capacity and higher power. Stable operation of the circuit system is crucial for ensuring the long-term safe operation of circuit components. To prevent abnormal conditions such as overload and short circuits, variable resistors play an increasingly important role. To ensure stable operation of the circuit system, resistors not only need to be precisely and continuously adjustable, but also require a rapid response to abnormal conditions.

[0003] Traditional variable resistors typically use solid metal wires wound around a sliding solid metal contactor to change the length of the wire, thus altering the resistance. Due to the low resistivity of metal, this type of rheostat has a limited resistance range and coarse control accuracy. While patent CN103280285A replaces the solid metal contactor with liquid metal, changing the height of the liquid metal to allow for different lengths of copper wire to be connected and thus change the resistance, it suffers from the following problems: the variable resistor in this patent application still changes resistance through the length of the copper wire, therefore, to achieve a wide range of resistance adjustments, sufficiently long copper wires must be wound, inevitably leading to a large variable resistor size; furthermore, although the liquid level is controlled by a solenoid valve, its response speed is still slower compared to piezoelectric ceramics. Patent CN106782961A applies for a rheostat based on liquid metal, which only replaces the metal wire with liquid metal, but the principle remains the same: changing resistance through the length of the liquid metal. Therefore, the channel for changing resistance is very long and narrow, leading to inaccurate resistance control and a large size. Summary of the Invention

[0004] This invention addresses the shortcomings and defects of existing technologies by providing a variable resistor and its control method that utilizes the piezoelectric effect to rapidly and precisely control the stretchability of liquid metal in order to ensure the safe and stable operation of circuit systems. In this invention, to respond quickly to abnormal operating conditions of the circuit system, the stretchability of the liquid metal is controlled by a voltage-controlled piezoelectric ceramic. Piezoelectric ceramics are characterized by rapid action and precise control, achieving microsecond-level response speeds. Unlike traditional variable resistors that change resistance by altering the length of a metal wire, the resistance of this invention is achieved by changing the length and cross-sectional area of ​​the liquid metal, mainly comprising two processes: In the first stage, the length and cross-sectional area of ​​the liquid metal change by altering the distance between the moving and stationary contacts; this process can be assumed to be a stage of constant volume change. In the second stage, in addition to the influence of displacement, the resistance of the liquid metal is significantly reduced due to the main influence of surface tension, thus greatly changing the resistance value. By controlling the stretchability of the liquid metal in these two stages, resistance changes of four orders of magnitude can be achieved.

[0005] The objective of this invention can be achieved through the following technical solutions.

[0006] A circuit breaker variable resistor for the power industry and its control method are disclosed. The variable resistor includes a control algorithm unit, a current detection unit, a displacement driving unit, a stroke amplification unit, and a resistance control unit.

[0007] The current detection unit is connected to the resistance control unit in sequence through the control algorithm unit, the displacement drive unit, and the stroke amplification unit;

[0008] The variable resistor control method includes the following steps:

[0009] S1: Connect the variable resistor to the circuit system, obtain the current in the line through the current detection unit, and determine whether there is an abnormality in the circuit system based on the detected current signal: if normal, do not perform any action; if abnormal, proceed to S2.

[0010] S2: Calculate the resistance value required for the circuit system to return to normal based on the detected abnormal current, then obtain the displacement of the displacement drive unit based on the resistance-displacement relationship, and finally determine the voltage signal to be output to the displacement drive unit based on this displacement.

[0011] S3: Based on the calculation results of the voltage signal output to the displacement drive unit, the displacement drive unit immediately responds and reaches the required displacement. The stroke amplification unit controls the displacement of the moving contact according to the displacement of the displacement drive unit, thereby realizing the control of the stretching degree of the liquid metal, completing the regulation of the resistance value, and bringing the circuit system back to normal.

[0012] S4: Jump to S1.

[0013] Preferably, the displacement driving unit contains a piezoelectric ceramic control circuit and at least one piezoelectric ceramic.

[0014] Preferably, the resistance control unit includes at least one liquid metal resistor structure;

[0015] Each liquid metal resistor structure includes a moving contact, a stationary contact, and liquid metal and its channels for connecting the two contacts;

[0016] Each liquid metal resistor structure is controlled by a piezoelectric ceramic, or multiple liquid metal resistor structures are controlled by a piezoelectric ceramic.

[0017] Preferably, the liquid metal is gallium or a multi-element alloy composed of gallium, indium, and tin;

[0018] Depending on the application environment, multi-element alloys with different melting points are prepared by stirring and mixing in a vacuum or glove box environment above 250°C.

[0019] Preferably, the current detection unit includes a current transformer and a current input module;

[0020] Current transformers are used to automatically detect the current in a circuit system to determine if there is an abnormality.

[0021] Beneficial technical effects of the present invention:

[0022] 1. Compared with complex mechanical transmission schemes, using piezoelectric ceramics as a displacement driving structure can achieve microsecond-level response speed, and has the advantages of more accurate and rapid response;

[0023] 2. Unlike traditional variable resistors that change resistance by altering the length of a metal wire, this invention utilizes liquid metal as a medium, which has a faster rate of movement and resistance change.

[0024] 3. Liquid metals are non-toxic and harmless, and have the advantages of high electrical conductivity and stable chemical properties. Attached Figure Description

[0025] Figure 1 This is the overall flowchart of the present invention.

[0026] Figure 2 This represents the initial state of the liquid metal in this invention.

[0027] Figure 3 This refers to the change state 1 of the liquid metal during the movement of the moving contact in this invention.

[0028] Figure 4 This refers to state 2 of the liquid metal during the movement of the moving contact in this invention.

[0029] Reference numerals: 1. Moving contact; 2. Liquid metal; 3. Stationary contact. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and do not limit the scope of the invention.

[0031] Example 1: As Figure 1 As shown, a circuit breaker variable resistor for the power industry and its control method include a control algorithm unit, a current detection unit, a displacement driving unit, a stroke amplification unit, and a resistance control unit.

[0032] Connect the variable resistor described in this article to a circuit system with a source voltage of 5V and a rated current of 10A.

[0033] like Figure 2 As shown, the diameter of the moving and stationary contacts is 10mm, and the two contacts are connected by liquid metal 2, with a height of approximately 2mm. The formula for calculating the initial resistance is as follows:

[0034]

[0035] Where ρ, l, and S are the resistivity, height, and cross-sectional area of ​​liquid metal 2, respectively. Since liquid metal 2 has excellent electrical conductivity, the initial on-resistance R0 of the single-contact variable resistor is approximately 7 μΩ, which can be ignored.

[0036] The current detection unit contains a current transformer, which can monitor the real-time current magnitude and current change rate di / dt, and transmit the detection results to the control algorithm unit.

[0037] The control algorithm unit compares the input current signal with a reference value to determine whether the circuit is in an abnormal operating condition. Simultaneously, the control algorithm calculates the resistance change ΔR required to return the circuit system to its rated state, and determines the response displacement of the piezoelectric ceramic based on the displacement-resistance relationship, thereby determining the input voltage U of the piezoelectric ceramic.

[0038] When the line current I1 is adjusted to 12A, the control algorithm unit determines that the circuit system is under overload conditions. To bring the circuit system back to its rated current, the variable resistor needs to change its resistance ΔR by approximately 0.083Ω. According to experimental data, a single contact can achieve a resistance change of 0.1Ω. Therefore, only one contact is needed to achieve a 0.1Ω resistance change to bring the line current back below its rated value.

[0039] Based on the resistance-displacement-voltage relationship, the displacement drive system controls the piezoelectric ceramic by outputting a voltage signal U, causing it to move to a specified displacement. Then, the stroke amplification unit converts the micro-displacement of the piezoelectric ceramic into a specified displacement d of the moving contact 1, ultimately achieving precise control of the stretched state of the liquid metal 2. This allows the circuit system to return to normal values. Simultaneously, the abnormal operating condition is recorded and an alarm is triggered. After the circuit problem is resolved or disappears automatically, the moving contact 1 returns to its initial state. During this process, the liquid metal 2 will... Figure 2 The initial state shown transforms into Figure 4 The change state shown is 2.

[0040] Example 2: As Figure 1 As shown, a circuit breaker variable resistor for the power industry and its control method include a control algorithm unit, a current detection unit, a displacement driving unit, a stroke amplification unit, and a resistance control unit.

[0041] Connect the variable resistor described in this article to a circuit system with a source voltage of 5V and a rated current of 1A.

[0042] like Figure 2 As shown, the diameter of the moving and stationary contacts is 10mm, and the two contacts are connected by liquid metal 2, with a height of approximately 2mm. The formula for calculating the initial resistance is as follows:

[0043]

[0044] Where ρ, l, and S are the resistivity, height, and cross-sectional area of ​​liquid metal 2, respectively. Since liquid metal 2 has excellent electrical conductivity, the initial on-resistance R0 of the single-contact variable resistor is approximately 7 μΩ, which can be ignored.

[0045] The current detection unit contains a current transformer, which can monitor the real-time current magnitude and current change rate di / dt, and transmit the detection results to the control algorithm unit.

[0046] The control algorithm unit compares the input current signal with a reference value to determine whether the circuit is in an abnormal operating condition. Simultaneously, the control algorithm calculates the resistance change ΔR required to return the circuit system to its rated state, and determines the response displacement of the piezoelectric ceramic based on the displacement-resistance relationship, thereby determining the input voltage U of the piezoelectric ceramic.

[0047] When the line current I1 is adjusted to 1.2A, the control algorithm unit determines that the circuit system is under overload conditions. To restore the power system to normal, the variable resistor needs to change a resistance ΔR of approximately 0.83Ω. According to experimental data, a single contact can achieve a resistance change of 0.1Ω. Therefore, nine contacts are needed to achieve a resistance change of 0.1Ω to bring the line current back below its rated value.

[0048] Based on the resistance-displacement-voltage relationship, the displacement drive system controls the piezoelectric ceramic by outputting a voltage signal, causing it to move to a specified displacement. Then, the stroke amplification unit converts the micro-displacement of the piezoelectric ceramic into a specified displacement 'd' of the moving contact 1, ultimately achieving precise control of the stretched state of the liquid metal 2. This allows the circuit system to return to normal values, records the abnormal condition, and triggers an alarm. Once the circuit problem is resolved or disappears automatically, the moving contact returns to its initial state. During this process, the liquid metal 2 will... Figure 2 The initial state shown transforms into Figure 4 The change state shown is 2.

[0049] Example 3: As Figure 1 As shown, a circuit breaker variable resistor for the power industry and its control method include a control algorithm unit, a current detection unit, a displacement driving unit, a stroke amplification unit, and a resistance control unit.

[0050] The variable resistor in this paper is connected to a circuit system with a source voltage of 5V and a rated current of 5A. The initial current of the circuit system is 2A.

[0051] like Figure 2 As shown, the diameter of the moving and stationary contacts is 10mm, and the two contacts are connected by liquid metal 2, with a height of approximately 2mm. The formula for calculating the initial resistance is as follows:

[0052]

[0053] Where ρ, l, and S are the resistivity, height, and cross-sectional area of ​​liquid metal 2, respectively. Since liquid metal 2 has excellent electrical conductivity, the initial on-resistance R0 of the single-contact variable resistor is approximately 7 μΩ, which can be ignored.

[0054] The current detection unit contains a current input unit, which can convert the desired current value input from the outside into an electrical signal and transmit the conversion result to the control algorithm unit.

[0055] The control algorithm unit compares the input current signal with the current value, determines the resistance ΔR required to change the circuit system current value to the desired current value, and determines the response displacement of the piezoelectric ceramic based on the displacement-resistance relationship, thereby determining the input voltage U of the piezoelectric ceramic.

[0056] The desired input current I1 is 3A. To make the circuit system operate at this target value, the variable resistor ΔR needs to be approximately 0.83Ω. According to experimental data, a single contact can achieve a resistance change of 0.1Ω. Therefore, eight contacts are needed to achieve a resistance change of 0.1Ω, and a ninth contact is needed to achieve a resistance change of 0.03Ω to bring the line current to the specified target value.

[0057] Based on the resistance-displacement-voltage relationship, the displacement drive system controls the piezoelectric ceramic by outputting a voltage signal, causing it to move to a specified displacement. Then, through the stroke amplification unit, the micro-displacement of the piezoelectric ceramic is converted into a specified displacement d for the moving contact 1, ultimately achieving precise control of the stretched state of the liquid metal 2, ensuring the circuit system operates in a specified state. During this process, the liquid metal 2 at the first 8 contacts will be... Figure 2 The initial state shown transforms into Figure 4 The change state 2 shown, while the liquid metal 2 at the 9th contact may be composed of... Figure 2 The initial state shown transforms into Figure 3 The form shown, morphology 1, may also be composed of... Figure 2 The initial state shown transforms into Figure 4 Form 2 is shown.

[0058] The above embodiments are descriptions of specific implementations of the present invention, and not limitations thereof. Those skilled in the art can make various modifications and changes without departing from the spirit and scope of the present invention to obtain corresponding equivalent technical solutions. Therefore, all equivalent technical solutions should be included in the patent protection scope of the present invention.

Claims

1. A variable resistor for circuit breakers used in the power industry and its control method, characterized in that, The variable resistor includes a control algorithm unit, a current detection unit, a displacement driving unit, a stroke amplification unit, and a resistance adjustment unit; The current detection unit is connected to the resistance control unit in sequence through the control algorithm unit, the displacement drive unit, and the stroke amplification unit; The variable resistor control method includes the following steps: S1: Connect the variable resistor to the circuit system, obtain the current in the line through the current detection unit, and determine whether there is an abnormality in the circuit system based on the detected current signal: if normal, do not perform any action; if abnormal, proceed to S2. S2: Calculate the resistance value required for the circuit system to return to normal based on the detected abnormal current, then obtain the displacement of the displacement drive unit based on the resistance-displacement relationship, and finally determine the voltage signal to be output to the displacement drive unit based on this displacement. S3: Based on the calculation results of the voltage signal output to the displacement drive unit, the displacement drive unit immediately responds and reaches the required displacement. The stroke amplification unit controls the displacement of the moving contact according to the displacement of the displacement drive unit, thereby realizing the control of the stretching degree of the liquid metal, completing the regulation of the resistance value, and bringing the circuit system back to normal. S4: Jump to S1.

2. The variable resistor for circuit breakers and its control method for the power industry according to claim 1, characterized in that, The displacement driving unit contains a piezoelectric ceramic control circuit and at least one piezoelectric ceramic.

3. The variable resistor for circuit breakers and its control method for the power industry according to claim 1, characterized in that, The resistance control unit includes at least one liquid metal resistor structure; Each liquid metal resistor structure includes a moving contact, a stationary contact, and liquid metal and its channels for connecting the two contacts; Each liquid metal resistor structure is controlled by a piezoelectric ceramic, or multiple liquid metal resistor structures are controlled by a piezoelectric ceramic.

4. A variable resistor for circuit breakers and its control method for the power industry according to claim 1, characterized in that, The liquid metal is gallium or a multi-element alloy composed of gallium, indium, and tin; Depending on the application environment, multi-element alloys with different melting points are prepared by stirring and mixing in a vacuum or glove box environment above 250°C.

5. A variable resistor for circuit breakers and its control method for the power industry according to claim 1, characterized in that, The current detection unit contains a current transformer and a current input module; Current transformers are used to automatically detect the current in a circuit system to determine if there is an abnormality.

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